So Gooch, Rick, and any other old timer with a TON of trigger time,
what gives? How can All of these be correct?Scott <xring@voicenet.com>USA - Thursday, October 08, 1998 at 16:22:09 (EDT)

Scott - On the wind formula, they can't all be correct. The problem
comes about due to using different drag co-efficents in the orignal model.
Since the Marine answer is 10 moa, I must assume that you are talking 168
gr. At SOTIC use a constant of 10 for the formula and while not dead on
it is within .5 moa at that range. If the G1 model is used you will get
one answer and if you use the correct boat tail co-efficent you will get
another. The rossettes were modeled on a multiple constant that had a basic
flaw and gave way toa low of a moa adjustment. The Sierra program uses
the G1 drag and comes up about 1.5 moa short. The army figures compute,
by error, to be .5 increments instead of 1 moa increments. So double the
army answer and you are close. I know, I really didn't answer your question,
but that's as close as I can come. I do know that if you use wind speed
in knots, times range in hundreds, divided by the constant of ten, you
will have a moa adjustment that will hit a mansized target at 1000 yards.
Use the same formula from 100 to 1000 and you will start out being .5 moa
too strong and end being .5 moa too weak. But, hey what's .5 inches to
5 inches among friends? By the way, don't forget spin drift.

On the windage issue. I have one thing to say. Remember guys all
of these formulas, charts etc are based on a crosswind with a single component
in "standard" conditions. We all know that it is a crap shoot. Gooch's
best advise is to shoot a lot, learn to read mirage and bury a lot of chicken
bones.

Damn, I'll try to get serious here.

All of the wind charts are only an attempt to get the shooter on
paper. No one can look at a chart and punch out X's all day just as I can't
read a book on nuclear physics and build an ion drive for a space ship
(where is he going with this huh?). Anyway, when I am shooting a lot, I
can usually look at the mirage or the observable conditions and be pretty
close on a wind call. If I haven't been shooting a lot, then I might as
well go with the voodoo.

Rick is on target with his suggestions on this so I will just shut
up and retire to my rack! Thanks Rick. I miss our IM's since I have had
to start this totally, bullshit civvy job.

WINDAGE:Using the Marine constant formula, C=10 gives you an answer in clicks
with 1 clk= .5 MOA (ie: M3A scopes) NOT in MOA. For MOA use C=20. These
give result very close to the chart in FM23-10, which I have found to be
quite accurate, given the limitations of all charts.Of course this is for M-118 only.Also spin drift is no joke. It has bitten me more than once.

Rick, thanks for the reply. The thing that makes the windage issue
so "interesting" is that at times I have used several of these formulas
and had center mass hits with them all, both in competition and on the
UKD range. What this tells me is that my wind estimation was OFF and I
was essentially just getting lucky. Example: The Army chart gives 4.5 minutes
for a full value 10 mph wind at 800 Meters. I have used that figure repeatedly
to ding the target. Yet when compared to the balistic program for the same
round, that call is off. So my assumption is that my wind call was actually
off. This is kind of like voodoo! Why is this bugging me right now? I am
trying to develop an accurate wind chart for my 26" PSS. Gathering all
the various data has brought to light (at least for me) all the varying
data out there. Guess I'll just have to stick with the Sierra program as
verifying the windage for every 100 yards and every 3 mph all the way to
1000 would take a life time in waiting for each condition.